It is known that when a rotor wheel is unfretted from its shaft to be inspected, it is necessary to adjust the dimension of its bore before fretting it on its shaft again. To adjust the dimension without affecting the characteristics of the basic metal, a sheet of nickel is deposited on said bore.
The bore of a wheel may also be coated with nickel to avoid fretting corrosion which may arise between two fretted parts.
Indeed, it is known that each time it is set in motion, the stress in the rotor of a turbine constituted by wheels fretted on a shaft is distributed in such a way that small differential movements between the fretted parts cause wear such as seizing or friction at the point where they are joined together which leads to particularly active corrosion when the ambient medium is aqueous.
The nickel deposit, which must be moderately or very thick (between 0.1 and several millimeters) is mechanically applied (foils, sockets, etc.).
To improve the quality of the deposit, in accordance with the invention, depositing is by electrolysis.